Armor-plate and other steel article.



I'. GIOLITTI.

ARMOR PLATFJ AND OTHER sTBRL ARTICLE.

APPLICATION FILED 00T.10, 1907.

1,043,416, Patented Nov. 5, 1912.

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g @MAM www www, w. ffm www formed' of successive FEDERICO GIOLITTI, 0F ROME, ITALY, .ASSIGNOR TO SOCIET ANONIMA ITALIANA. GIO.

i ANSALDO ARMSTRONG & CO., OF GENOA, ITALY, A CORPORATION OF ITALY.

ARMOR-PLATE AND OTHER STEEL ARTICLE.

1,043,416. Original application led September 6,

VTo all whom it may concern:

Be it known that I, FEDERICO GloLrr'rI, a

Vsubject ofthe King of Italy, residing in Rome, Italy, have invented certain new and useful Improvements in Armor-Plates and other Steel Articles, of which the following is a specification.

This application has been divided out of an application tiled in the `United States Patent Oiice September 6, 1906, Serial No. 333,409.

This invention refers to the manufacture of armor plates or any other objects of ordinary carbon steel as well as of any other special ternary, quaternary and like steel, layers alternately more or less hard, tenacious and elastic.

This invention consists in submitting the plates or other objects of homogeneous steel possessing a small or large proportion of carbon, to a series of success1ve carbonizations or decarbonizations, or both, regulated as regards their duration, and as regards the temperature at `which they are produced, so as to obtain at the interior and on one or more surfaces two or more layers strongly carbonized, tenacious, having a less hard and more plastic.

clearly crystalline structure and capable of being strongly tempered, the said layers being alternated with two or more layers having a slight proportion of carbon which consequently, even after the tempering, are

The ligure of the drawing indicates a steel plate made according to the present invention in which there is a Zone b containing less carbon than the inner portion a of the article, and an outer zone c containing a greater proportion of carbon than the adjacent inner zone b. K

In order to obtain this result advantage is taken of the laws that govern the velocity ofdiffusion of the carbon in' iron and in steel, at the various temperatures, at the time of the carbonization, or of the de-carbonization, as well as of the laws which govern the limit of saturation of the iron as regards the carbon, which varies also with the variations of temperature. The operation is effected in the following manner The ordinary ternary, quaternary or like steel ingot, before, or after, it has een submitted to the ordinary mechanical manipulations (pressing, rolling, hammer- Specification of Letters Patent.

1906, Serial No. 333,409. Divided and this application led October 10, 1907. Serial No. 396,863.

Patented Nov. 5, 1912.

ing and lthe likey that transforms it into the plate or other object of the desired shape orV form, is submitted first to a treat ment which varies according to the pron Y portion of carbon contained by the ingot;- and: then to ulterior treatments, described hereafter; and which treatments constitute the essential part of the present invention, and impart to the plate or other object special resisting and other advantageous qualities.

In the case Where the plate has only a small proportion of carbon the preliminary operation consists in strongly carbonizing it on one of these surfaces by proceeding with the carbonization to the depth necessary so as to obtain, by means of the tempering, the hard deeper layer in the desired position and presenting the desired degree of carbonization. This carbonization can easily be obtained by the ordinary method used by maintaining the plate for a suf- Iiciently long period, and at a suitable temperature below the highest critical point, in contact with granular carbonaceous substances compressed against one of its surfaces, or in an atmosphere of carbureted gas, limiting also in this case the contact of these latter to only one surface of the plate.

In the case where,on the contrary, it refers to an ingot and consequently a plate having a high proportion of carbon, the rst operation to which the plate has to be submitted is inverse as regards that of the receding case. In this second case the plate 1s submitted to a de-carbonization on the one or both of its surfaces. This de-carbonization is effected by heating the said plate for a given time and at a given temperature below the highest critical point with suitable mixtures of metallic oXids reduced to a suitable degree of sub-division and firmly compressed against the surface or surfaces from which it is desired that the cle-carbonization may extend to the interior of the plate.

The de-carbonization will be carried to a different degree, and to a dilcrent depth, on the two surfaces by suitably regulating the temperature and the duration of the opera tion for each of them. This latter car. at a certain moment be interrupted on one of the surfaces by substituting for the mixture of oxids, a granular compact inert substance,

In any case, it is always possible, by carefully applying the law of diifusion of the carbonization and the de-carbonization as regards the temperatures, and .the times, to vcontinue th'e operation until a layer of given carbonization and thickness 'and situated at a determined position at the interior of the plate is obtained. Y

The same results can be obtained in the rst case, for example, when startin with a plate having a slight proportion o carbon and which has subsequently been carbonized on one of its surfaces to a suitable depth as has been described above. In vthis instance, the same result as 'indicated' above is obtained by submitting the plate to a suitable that there willresultat the interior of the "plate, a more orlessstrongly carbonized first carbonization and by that of the ex layer of the desiredv thickness and situated at the desired depth. This depth is only regulated by the position of the limit of the treme limit of the subsequent de-'carbonization. Obviously, the said successive and alternative operations of carbonization and de-ca-rbonization, can`v be,l repeated one or more times. .There canthus be obtalned in the mass of steel, a series of 'layers more or less strongly. carbonized, `alternating with layers weak-in carbon, so that the proportion of carbon varies gradually and without discontinuity when passing from one layer to 'the contiguous layer. The said operations can "ordinarily be effected simultaneously on both surfaces of theplate. y

If itis desired to` give to one or to both surfaces a -large proportion of carbon in order for example to be ableto subsequently hardenlthem to a high degree by the tempering, the steel body should always be submittedto a final supercial and more intense t faces, orvon both. l f- On .subsequently` applying the various methods used for the simple or multiple homogeneous temperingof ordinary steels and special-steels, a body of steel ,will bev vobtainedvarying gradually fromone layer 'to the otherlas' 'regards-hardness, tenacity and elasticity.

ness .and thev composition of Athe various layers (that is'tofs'ay their quality as lregards the tempering) this permits the employment v of the body of steelffor a great-number 'of applications in which the heterogeneousness ture, of armor plates for ships. In these plates the plastic and tenacious mass which .Claim or rapld carbonlzation onK one of the surforms thebase'and the support ofthe layer, strongly hardened by the carbonizing and by the tempering under given conditions, will -be substltuted by the mass..itse1f supported by one or several very hard and tenaclous/ in pefforating the Very hard and very tenacious exterior surface. This will permit considerable decrease in the thickness of the v plates for equal resistance, and for equal thickness, will considerably increase the resistance.

For example, to treat a piece' of mild steel showing the following composition: carbon 0.7%, manganese 0.60%, silicon 0.12%, sulfur 0.03%, phosphorus 0.02%,.With the intention of obtaining two carbureted zones fseparated from each other by a' decarbureted zone, so that, for instance, on proceedlng inwardly from the outer face of the piece the .percentage ofy carbon decreases from 0.3%

at the surface to 0.1% at 3 mm. depth, then remains unchanged up to 6 mm. depth and increases again to .8% at 9 mm. depth, and again decreases to .2% at 12mm. depth. It will be necessary to adopt the following courses to obtain ith/is result: 1st step, heat- :ing the steel piece up, to 1000 degrees C. .during 90 hours in contact with a mixture consisting of threey parts of silicious sand and one part of ferrie oxid (F203). 2nd step, lheating the steel piece up to 1100 degrees C. during 20 hours in contact with a l granular mixture consisting of two parts of charcoal and one part of'vbarium carbonate.

3rd step, heating up to 1000 degrees C. dur#l ing 6 hours in contact with the same mixture lof' silicious` sand and ferrie oxid used duringv the first step of the treatment.

Having thus described my invention, I

1. A steel plate or other articleof unitary Q structure having on one or more surfaces a "zone formed by diffusion of carbon in such zone whereby the proportion 'of the carbon is less than in the other part of such article, andV one or more lsub-zones formed in the said zone by diffusion of carbon whereby the A.

proportion of, carbon in such sub-zones is y v v greater than'in the other parts of the zone. By vary-ing therelative position, the th1ck.

2. A steel 'plate or other articleof unitary structure having on lone or'more surfaces a zone 'formed by diffusion of carbon whereby the proportion of the carbonlin such zone...

is less than in the other part of such article, and one or more sub-zones formed inthe said zone by diffusion of carbon whereby the proportion of carbon in such sub-zones is' r zone formed by diffusion of carbon whereby the proportion of the carbon in such zone is less than in the other part of such article, and one or more sub-Zones formed in the said zone by diffusion of carbon whereby the proportion of carbon in such sub-zones is greater than in the other parts of the plate.

4. A steel plate or other article of unitary structure having on one or more surfaces a zone formed by diusion of carbon whereby the proportion of the carbon in such zone is different from the other part of such article, and one or more sub-Zones formed in the said zone by diffusion of carbon whereby the proportion of carbon in such sub-zones varies from the other part of the zone and also from the other part of the article, one of the said zones having the proportion of carbon less than in the inner portion of the article.

A steel plate or other article of unitary structure, having on one or more surfaces a series of three zones formed by diffusion of carbon in which the proportion of carbon varies in the adjacent zones.

6. A steel plate or other article of unitary structure, having on one or more surfaces a series of three zones formed by diffusion of carbon in which the proportion of carbon varies in the adjacent zones, the second zone having less proportion of carbon than the outer zone, and the third zone having a greater proportion of carbon than in the second zone.

Signed at Nos'. 9-15 Murray street, New York, N. Y., October 1st, 1907.

FEDERICO GIOLITTI.

Witnesses:

WILLIAM H. REID, FRED. J. DOLE. 

